Probably already been said, but bots.

After reading up a bit on it, it sounds like most servers have what I've been seeing on my server: a collection of bot accounts (conveniently in the same FC) where one just sits in an apartment 24/7 crafting, and the others, who are leveled only as high as they need to be to use retainers, rotate in and out to constantly undercut on the MB. They have dozens of retainers and are selling pretty much every possible high priced craftable item you can think of. If you want to sell one of those items, you are out of luck, because you are competing with a script that will undercut you every time you drop the price.

I know that selling stuff on the MB is a minor aspect of the game, but it's one that always used to be fun. That's over now. Between the bots owning the market for anything profitable, and the housing demolition hold virtually ending the market for housing items, there's very little of value one can sell on the MB anymore.

And it's true that these factors have cratered prices for everything in general, meaning you don't need much gil anymore to get what you want, but it's still an aspect of the game that's been destroyed.